str1 = "hello world"
str2 = 'hello world'
str3 = '''hello 
world'''
print(str1)
print(str2)
print(str3)
print('hel\'lo world')  # \ 转义符
print('123---{0}---{1}---{2}'.format(4, 5, 6))
str1 = 'hello'
print(f'123---{str1}')

# 显示进度
for i in range(0, 101, 2):
    print("======================开始下载============================")
    if i == 100:
        print("下载完成")
    else:
        str4 = "*" * (i // 2) + "." * ((100 - i) // 2)
        print(f'{i}%[{str4}]')